13,742 research outputs found
An investigation into variables moderating the outcomes of mindfulness meditation
Mindfulness-based Cognitive Therapy’s (MBCT) application has become increasingly widespread following its establishment as an effective treatment for depression relapse prevention. Mindfulness meditation (MM) is an integral component of MBCT, but little research has looked at MM guidance instructions themselves. This study aimed to compare the efficacy of two types of MM instruction in improving state affect, in addition to examining whether the type of instruction interacted with the trait characteristic of self-criticism to influence positive affect specifically. Seventy participants were randomised to groups doing either a concentration-oriented or an acceptance-oriented 10-minute MM of the breath. Changes between the groups in pre- to post-meditation state affect, state mindfulness and state concentration were analysed using a three-way mixed ANOVA, with baseline self-criticism entered as a between-participant variable to investigate its hypothesised interaction (or, moderation) with meditation type and outcomes across time.
Significant improvements in mindfulness, concentration and negative affect were seen across both meditations, with the concentration-oriented meditation improving concentration significantly more than the acceptance-oriented condition. Further, those categorised as highly self-critical demonstrated a significant reduction in negative affect compared to no reduction for low self-critical participants. The hypothesised interaction between self-criticism and meditation type was not found. Modifying MM of the breath instructions may hold potential in selectively targeting outcomes such as concentration, and self-criticism may predict whether non-clinical participants benefit from improved mood following either form of brief MM. The study’s findings are discussed in addition to identifying limitations, clinical implications and directions for future research
Active versus passive damping in large flexible structures
Optimal passive and active damping control can be considered in the context of a general control/structure optimization problem. Using a mean square output response approach, it is shown that the weight sensitivity of the active and passive controllers can be used to determine an optimal mix of active and passive elements in a flexible structure
Enhancement of the conductivity of Ba2In2O5 through phosphate doping
In this paper, we demonstrate the successful incorporation of phosphate into Ba2In2O5, which leads to the conversion from an orthorhombic to a cubic unit cell. The resulting increased oxygen vacancy disorder leads to an enhancement in the oxide ion conductivity at low temperatures. In addition, in wet atmospheres, significant proton conduction is observed
A disturbance based control/structure design algorithm
Some authors take a classical approach to the simultaneous structure/control optimization by attempting to simultaneously minimize the weighted sum of the total mass and a quadratic form, subject to all of the structural and control constraints. Here, the optimization will be based on the dynamic response of a structure to an external unknown stochastic disturbance environment. Such a response to excitation approach is common to both the structural and control design phases, and hence represents a more natural control/structure optimization strategy than relying on artificial and vague control penalties. The design objective is to find the structure and controller of minimum mass such that all the prescribed constraints are satisfied. Two alternative solution algorithms are presented which have been applied to this problem. Each algorithm handles the optimization strategy and the imposition of the nonlinear constraints in a different manner. Two controller methodologies, and their effect on the solution algorithm, will be considered. These are full state feedback and direct output feedback, although the problem formulation is not restricted solely to these forms of controller. In fact, although full state feedback is a popular choice among researchers in this field (for reasons that will become apparent), its practical application is severely limited. The controller/structure interaction is inserted by the imposition of appropriate closed-loop constraints, such as closed-loop output response and control effort constraints. Numerical results will be obtained for a representative flexible structure model to illustrate the effectiveness of the solution algorithms
Spin swap vs. double occupancy in quantum gates
We propose an approach to realize quantum gates with electron spins localized
in a semiconductor that uses double occupancy to advantage. With a fast
(non-adiabatic) time control of the tunnelling, the probability of double
occupancy is first increased and then brought back exactly to zero. The quantum
phase built in this process can be exploited to realize fast quantum
operations. We illustrate the idea focusing on the half-swap operation, which
is the key two-qubit operation needed to build a CNOT gate.Comment: 5 pages, 2 figure
Evaluation of ERTS-1 image sensor spatial resolution in photographic form
There are no author-identified significant results in this report
Quantum and Fisher Information from the Husimi and Related Distributions
The two principal/immediate influences -- which we seek to interrelate here
-- upon the undertaking of this study are papers of Zyczkowski and
Slomczy\'nski (J. Phys. A 34, 6689 [2001]) and of Petz and Sudar (J. Math.
Phys. 37, 2262 [1996]). In the former work, a metric (the Monge one,
specifically) over generalized Husimi distributions was employed to define a
distance between two arbitrary density matrices. In the Petz-Sudar work
(completing a program of Chentsov), the quantum analogue of the (classically
unique) Fisher information (montone) metric of a probability simplex was
extended to define an uncountable infinitude of Riemannian (also monotone)
metrics on the set of positive definite density matrices. We pose here the
questions of what is the specific/unique Fisher information metric for the
(classically-defined) Husimi distributions and how does it relate to the
infinitude of (quantum) metrics over the density matrices of Petz and Sudar? We
find a highly proximate (small relative entropy) relationship between the
probability distribution (the quantum Jeffreys' prior) that yields quantum
universal data compression, and that which (following Clarke and Barron) gives
its classical counterpart. We also investigate the Fisher information metrics
corresponding to the escort Husimi, positive-P and certain Gaussian probability
distributions, as well as, in some sense, the discrete Wigner
pseudoprobability. The comparative noninformativity of prior probability
distributions -- recently studied by Srednicki (Phys. Rev. A 71, 052107 [2005])
-- formed by normalizing the volume elements of the various information
metrics, is also discussed in our context.Comment: 27 pages, 10 figures, slight revisions, to appear in J. Math. Phy
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